package extend;

import java.util.Scanner;

public class Day_04 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        System.out.print("请输入一个值:");
        //1. 接收用户输入的一个整数num，判断它的正负零值，
        // 正数则输出"+"，负数则输出"-"，0则输出"0"
        int num = scan.nextInt();
        if (num == 0) {
            System.out.println("该值为:0");
        }else if (num > 0) {
            System.out.println("该值为:+");
        }else {
            System.out.println("该值为:-");
        }

        //2. 接收用户输入的年份year和月份month，计算该年该月的天数，并输出
        System.out.print("请输入一个年份和月份:");
        int year = scan.nextInt();
        int month = scan.nextInt();
        int days = 0;
        if (month < 13 && month >0) {
            switch (month) {
                case 1: case 3: case 5: case 7: case 8: case 10: case 12:
                    days = 31;
                    break;
                case 4: case 6: case 9: case 11:
                    days = 30;
                    break;
                case 2:
                    if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
                        days = 29;
                    } else {
                        days = 28;
                    }
                    break;
            }
            System.out.println(year + "年的" + month + "月份有" + days + "天");
        }else {
            System.out.println("非法年月份!!!");
        }

        //3. 利用循环语句while计算数字1到100的和，并输出
        int i = 0;
        int sum = 0;
        while (i<+100){
            sum += i;
            i++;
        }
        System.out.println("1-100的和为:"+sum);














    }
}
